Torque Staff Report
One of the first modifications many make to their Jeeps is to add larger tires. Often, this requires a suspension lift as well to create the clearance needed to slap on that larger rubber. Both of these are a great way to improve off-road performance, while also giving the vehicle a more rugged appearance.
However, these modifications also have a direct effect on the Jeep's power and driving behavior. That's because more tire means more force is needed to get (and keep) those things turning. And if you grow the tire size enough, then the Jeep's current gearing may no longer be satisfactory — especially when hill climbing to trying to quickly accelerate.
Adding horsepower or torque can help mitigate this loss, but these power gains will not change your Jeep's shift points and could actually hasten the decline of that transmission.
So, how do you know what will work the best?
Well, to answer that question, we've developed this chart to help you select the optimum gear ratio for your desired tire size.
First, determine your original gear ratio and tire size, and then intersect that with your approximate RPM at 65 miles-per-hour. If you are not sure what gears are on your Jeep, here are a few tips to determine gearing. Additionally, here is an easy way to understand your Jeep's tire size. Next, find your new tire size and again match it with the closest RPM at that 65 miles-per-hour speed. This will be the minimum recommended new gear ratio.
If you are interested in a change that provides more power or better fuel mileage, use the color coding as a guide.
Not sure about what size tires to choose, we can help you make the right decision.
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Highway Driving, Good Fuel Economy |
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| Daily Driver, Best Overall Performance | |
| Most Power and Towing, Reduced Fuel Economy |
This chart is based on 65 MPH and a gear ratio of 1:1, on a manual transmission in 4th gear. Please NOTE: If you have an automatic transmission your RPM will higher due to slippage in the transmission and the torque converter. With an overdrive transmission your RPM in overdrive will be 15% to 30% less than indicated.
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